Cascara

Rhamnus purshiana - Erect, tall shrub or small tree to 10m tall, with thin., smooth, silver-grey, numbingly bitter bark. Leaves alternate, may seem almost opposite on new growth, deciduous, egg-shaped to oblong. dark glossy green 6-12 cm long, finely toothed, strongly pinnately veined in furrows, the surface washboardy. Flowers greenish-yellow, small 3-4 cm long, 4 sepals, petals and stamens; 5-50 in stalked umbrella-shaped clusters in the axils of leaves. Fruits blue-black to purplish-black berries; edible but not incredible. Grows in fairly dry to wet, often shady sites, most commonly in mixed woods, at low to middle elevations.